fix(app): restore line numbers in diff gutter and add tap-to-comment

The gutter was showing the message-circle icon on every reviewable line on
native and on compact form factors, displacing the line number whenever
review draft mode was active. Restore the default by computing showAction
purely from interaction state (hover/press), comment presence, and editor
visibility — drop the showPersistentAction flag and the isNative bias.

Tap on the gutter directly opens the inline review editor on every
platform. On native, long-pressing a line of code (350ms) also opens the
editor via a new LongPressableLine wrapper, preserving web text selection.

packages/app/src/review/surface.test.tsx

@@ -130,12 +130,12 @@ function target(overrides: Partial<ReviewableDiffTarget> = {}): ReviewableDiffTa
 }
 
 const EMPTY_COMMENTS: ReviewDraftComment[] = [];
+const COMMENT_LIST: ReviewDraftComment[] = [comment()];
 
 function buildReviewActions(overrides: Partial<InlineReviewActions> = {}): InlineReviewActions {
   return {
     commentsByTarget: new Map(),
     editor: null,
-    showPersistentAction: false,
     onStartComment: vi.fn(),
     onEditComment: vi.fn(),
     onCancelEditor: vi.fn(),
@@ -173,13 +173,10 @@ describe("useInlineReviewController", () => {
     const firstKey = "review:key-1";
     const secondKey = "review:key-2";
     const { result, rerender } = renderHook(
-      ({ reviewDraftKey }) =>
-        useInlineReviewController({ reviewDraftKey, showPersistentAction: true }),
+      ({ reviewDraftKey }) => useInlineReviewController({ reviewDraftKey }),
       { initialProps: { reviewDraftKey: firstKey } },
     );
 
-    expect(result.current.showPersistentAction).toBe(true);
-
     act(() => result.current.onStartComment(reviewTarget));
     expect(result.current.editor).toEqual({ target: reviewTarget, commentId: null, body: "" });
 
@@ -243,16 +240,7 @@ describe("git diff inline review helpers", () => {
     expect(
       getInlineReviewThreadState({
         reviewTarget: target(),
-        reviewActions: {
-          commentsByTarget,
-          editor: null,
-          showPersistentAction: false,
-          onStartComment: vi.fn(),
-          onEditComment: vi.fn(),
-          onCancelEditor: vi.fn(),
-          onSaveEditor: vi.fn(),
-          onDeleteComment: vi.fn(),
-        },
+        reviewActions: buildReviewActions({ commentsByTarget }),
       })?.comments,
     ).toEqual([comments[0]]);
   });
@@ -261,16 +249,10 @@ describe("git diff inline review helpers", () => {
     const leftTarget = target({ side: "old", lineNumber: 8, oldLineNumber: 8 });
     const rightTarget = target();
     const rightComment = comment();
-    const actions: InlineReviewActions = {
+    const actions = buildReviewActions({
       commentsByTarget: groupInlineReviewCommentsByTarget([rightComment]),
       editor: { target: rightTarget, commentId: null, body: "" },
-      showPersistentAction: false,
-      onStartComment: vi.fn(),
-      onEditComment: vi.fn(),
-      onCancelEditor: vi.fn(),
-      onSaveEditor: vi.fn(),
-      onDeleteComment: vi.fn(),
-    };
+    });
 
     const rowState = getSplitInlineReviewThreadState({
       left: leftTarget,
@@ -292,7 +274,7 @@ describe("git diff inline review helpers", () => {
     ).toEqual([{ position: "sticky", left: 0 }, { width: 320 }]);
   });
 
-  it("keeps the gutter add-comment target accessible", () => {
+  it("keeps the gutter add-comment target accessible and clicking opens the editor", () => {
     const onStartComment = vi.fn();
     const reviewTarget = target();
     const { getByLabelText } = render(
@@ -300,7 +282,6 @@ describe("git diff inline review helpers", () => {
         reviewTarget={reviewTarget}
         comments={EMPTY_COMMENTS}
         isEditorOpen={false}
-        showPersistentAction={false}
         onStartComment={onStartComment}
       >
         <span>2</span>
@@ -312,14 +293,41 @@ describe("git diff inline review helpers", () => {
     expect(pressablePropsByLabel.get("Add review comment")?.hitSlop).toBe(SMALL_ACTION_HIT_SLOP);
   });
 
-  it("replaces the line number with the message icon in the same gutter cell", () => {
+  it("shows the line number by default and replaces it with the icon when comments exist or the editor is open", () => {
     const reviewTarget = target();
-    const { container, queryByText } = render(
+    const { container, queryByText, rerender } = render(
       <InlineReviewGutterCell
         reviewTarget={reviewTarget}
         comments={EMPTY_COMMENTS}
         isEditorOpen={false}
-        showPersistentAction
+        onStartComment={vi.fn()}
+      >
+        <span>2</span>
+      </InlineReviewGutterCell>,
+    );
+
+    expect(queryByText("2")).toBeTruthy();
+    expect(container.querySelector("[data-icon='MessageCircle']")).toBeNull();
+
+    rerender(
+      <InlineReviewGutterCell
+        reviewTarget={reviewTarget}
+        comments={COMMENT_LIST}
+        isEditorOpen={false}
+        onStartComment={vi.fn()}
+      >
+        <span>2</span>
+      </InlineReviewGutterCell>,
+    );
+
+    expect(queryByText("2")).toBeNull();
+    expect(container.querySelector("[data-icon='MessageCircle']")).toBeTruthy();
+
+    rerender(
+      <InlineReviewGutterCell
+        reviewTarget={reviewTarget}
+        comments={EMPTY_COMMENTS}
+        isEditorOpen
         onStartComment={vi.fn()}
       >
         <span>2</span>